在Mule流中使用SQL结果变量

Question

I got a Mule flow with 2 queries. The first simply validates if a username is duplicated.

Does something like this: SELECT count(*) AS TOTAL FROM user_tests WHERE username = #[json:username] AND test_message_title = #[json:test_message_title]

The second one does an INSERT if TOTAL = 0.

Now, i want to use the variable "TOTAL" in a choice inside the same flow. How do i do it?

Tried #[TOTAL=0], tried #[variable:TOTAL=0], and many others but couldn't make it work.

EDITED: I made a java component that retrieve the "0" or whatever number from the payload. How do i make the choice expression to compare it?

Tried using Integer.valueOf(message.payload) = 0 in the choice expression but i get an InvalidExpressionException.

This is my entire flow:

<flow name="ADMIN_INSERT_TEST_FILE" doc:name="ADMIN_INSERT_TEST_FILE">
    <ajax:servlet-inbound-endpoint channel="/admin/save_test_message" responseTimeout="10000" doc:name="Ajax"/>
    <set-variable variableName="#['saved_payload']" value="#[payload]" doc:name="Save original payload"/>
    <jdbc:outbound-endpoint exchange-pattern="request-response" queryKey="validate_test_name" queryTimeout="-1" connector-ref="ExtendedRoutingConnector" doc:name="validate duplicated test name">
        <jdbc:query key="validate_test_name" value="SELECT count(*) AS TOTAL FROM user_tests WHERE username = #[json:username] AND test_message_title = #[json:test_message_title]"/>
    </jdbc:outbound-endpoint>
    <logger message="#[message.payload[0].TOTAL]" level="INFO" category="Total" doc:name="Logger"/>
    <choice doc:name="Choice">
        <when expression="#[message.payload[0].TOTAL == 0]">
            <processor-chain>
                <set-payload value="#[variable:saved_payload]" doc:name="Save Payload"/>
                <jdbc:outbound-endpoint exchange-pattern="request-response" queryKey="insert_user_test_message" queryTimeout="-1" connector-ref="ExtendedRoutingConnector" doc:name="insert user test message">
                    <jdbc:query key="insert_user_test_message" value="INSERT INTO user_tests (username, test_message_title, user_test_message) VALUES (#[json:username], #[json:test_message_title], #[json:message])"/>
                </jdbc:outbound-endpoint>
            </processor-chain>
        </when>
        <otherwise>
            <processor-chain>
                <logger message="Name #[json:test_message_title] already exists" level="INFO" doc:name="Logger"/>
            </processor-chain>
        </otherwise>
    </choice>
</flow>

Thanks in advance.

Answer 1

Use MEL:

#[message.payload[0].TOTAL == 0]

This will retrieve the value of the TOTAL column from the first row returned by your SELECT query.